Determination of the loss coefficient of elbows in the flow of low-density spherical capsule train

Design parameters of a pipelines capsule flow can be calculated if dependence of pressure drops on flow velocity and capsule concentration of such pipelines are known. For this purpose, loss coefficients of elbows were studied experimentally in pipeline loop of I.D. 0.1 m. Elbows with central angles of 90° and 45° made of PVC were used for low-density spherical capsule train flow. The outer diameter and relative density of the capsules were 0.08 m and 0.87, respectively; the pressure drops were measured at Reynolds number range 2 × 104 < Re < 1 × 105 and for a transport concentration from 5% to 25%. Increments of the pressure gradient become larger at higher velocities and solid phase concentrations. The pressure gradients that occurred at the 90° elbow were higher than that occurred at the 45° elbow. Loss coefficient of the 90° elbow for the same flow velocity and capsule concentration in the capsules–water mixture flow is from 3 to 2 times higher than the loss coefficient at the 45° elbow.